Many routine, as well as specialized, operations in a typical laboratory require the transfer of known volumes of liquids. It is often important to ensure that the liquid dispensing devices perform within pre-established specifications. International guidelines have been established with regard to acceptable tolerances for various types of liquid dispensing devices. Users of these devices usually establish a routine for accuracy verification of their devices which includes periodic testing.
Several prior art techniques are commonly used for volumetric verifications including gravimetry, photometry and volumetry. Each of these techniques has one or more drawbacks that may be desirable to overcome.
For example, gravimetry is time consuming and is susceptible to error because a highly controlled environment is required. Heat from an operator's hand is a potential source of error. Photometry, due to Beer's law of absorbance, requires several different reference dye solutions to cover an appreciable range of delivery volumes. Also, a skilled technician is required to operate the spectrophotometer. Volumetry, essentially an acid-base titration, is likewise subject to operator and other sources of potential error.